18-Substituted steroids. Part 10. Synthesis of 16α,18,21-trihydroxypregn-4-ene-3,20-dione (16α,18-dihydroxy-11-deoxycorticosterone)

Abstract

The title compound has been prepared from 3β-acetoxy-16α-hydroxypregn-5-en-20-one by two routes, each involving application of the ‘hypoiodite’ reaction sequence [Pb(OAc)₄-I₂-hν; oxidation; solvolysis] to a 16α-acyloxypregnan-20β-ol derivative, to obtain the corresponding 18-hydroxypregnan-20-one (as 18,20-hemiacetal), with subsequent acetoxylation at C-21, and selective oxidation at C-3.